Photonic crystals have opened up a new realm of possibilities within semiconductor optics. Photonic crystals include periodic dielectric structures that can be used to create nano-scale optical waveguides, light trapping nano-cavities, and may be combined with existing device structures to provide a unique set of properties. Through the introduction of a photonic crystal into a semiconductor laser, new properties are obtained including coherent oscillation, very low divergences (as low as 1 degree), beam steering, high power single mode operation, power scaling, and wavelength selectivity.
The generation of high single-mode powers is generally accomplished by increasing the area of a surface emitting laser. For devices utilizing a vertical cavity the area over which single-mode emission is obtained is limited to a few microns. For external cavity surface emitting lasers and photonic crystal surface emitting lasers (PCSELs) the area of the device which can support a single-mode is limited by difficulties in obtaining uniform current injection and heat extraction. Often in a circular device power scales linearly with diameter rather than area.
The present invention relates to an improved laser structure. Certain embodiments of the present invention provide improvements and/or benefits that go beyond prior art laser structures.